The present invention relates to a system for disposing of bilge water in marine vessels in a non-polluting, environmentally protective manner, as well as in a safe, automatic and dependable manner with respect to the vessel's operation.
Virtually all larger ships and boats have bilge water in various quantities that must be periodically disposed of. Ship water invariably is contaminated with oil from cargo tank washdowns, engine oil leakage, and other sources, as well as other impurities, such as cleaning compounds (detergents, caustics), cargo leakages, and other such remnants of activities carried out on board the vessel at one time or another during its operation. Previously, and even in present times, the bilge of the vessel is simply pumped out and overboard, resulting in serious contamination of waterways and harbors. To meet this environmental threat, governmental jurisdictions around the world have enacted various legislative mandates against the discharge of water pollutants from vessels, particularly oily contaminants. Since bilge water is a substantial source of such oil contaminants, the need had long been recognized for a system to remove the oil from the bilge water prior to discharge of the water overboard and to enable recovery of the oil itself, a valuable commodity. In known systems, bilge water is cleaned of its oil content by centrifugal systems, gravitational settling tanks, and filters. These systems have their own advantages as well as their shortcomings, depending on operating conditions of the vessels in which they are installed and depending on the nature of the bilge fluids themselves.
It is known, for example, that filtration of oil from bilge water will work well where the oil content of the bilge water is small. However, where substantially pure oil slugs are encountered, filtration becomes a most inefficient and tedious method of cleaning the bilge effluent, since the filter units normally installed on vessels for this purpose are limited in the amount of oil they can remove by their physical size and flowrate capacity. They require constant changing of the filtration screens or cartridges when the units have reached their limits of oil removal ability, and such limits are reached quickly when a substantial amount of oil is contained in the bilge water. Since such filter changes must be done by a ship maintenance man or crew, and since most filtration systems shut down the filter unit automatically when their capacity is reached, the cost in terms of man hours and filter units is substantial.
The inventor and assignee of the present application are aware that previous efforts to separate oil from bilge water include such systems as shown in U.S. Pat. No. 1,586,449 to Jones, as well as U.S. Pat. No. 1,921,689 to Meurk, and more recent Patent No. 3,425,556 to Volker. Still other prior art examples are seen in U.S. Pat. No. 1,406,950 to Fackert and U.S. Pat. No. 1,425,289 to Robinson. They are also aware of a floating dome-type oil-water separation unit such as described in U.S. Pat. No. 3,628,660 to in'tVeld.
Applicant and assignee are also aware of previous efforts to dispose of human waste products on vehicles or vessels by burning or evaporating the waste products using the engine of the vehicle or vessel as the heat source, particularly the exhaust manifold or stack. U.S. Pat. Nos. Re.26,891, U.S. Pat. No. 3,504,797, 3,615,010 and others issued to James S. Reid and assigned to Standard Products Company of Cleveland, Ohio are illustrative of waste water evaporative systems using the exhaust manifold of an internal combustion engine as the heat source. The following patenst show additional illustrations of systems known in the prior art for disposing of human waste water through vaporization thereof in the exhaust stream of the internal combustion engine of a vehicle: U.S. Pat. Nos. 2,565,720, 3,731,490, and 3,740,773.
The inventor is unaware, however of any prior art usage of a bilge water disposal system using a floating dome oil separating unit for removing oil contaminant from the bilge water in combination with an exhaust stack vaporizor for disposing of the water thus separated from the oil in a fully automatic and continuously operating manner under the control of a sophisticated regulation arrangement that ensures safe operation of the system at all times. The present invention has grown out of the recognition that such a system is needed in the maritime field, and, as will be set forth in detail below, represents a unique and marked advance in the art.
The floating dome oil separator referred in herein is shown in two of its basic formats in the above-mentioned U.S. Pat. No. 3,628,660 as well as in British Pat. No. 1,212,553 published Nov. 18, 1973, the latter being based on a convention priority application in the Netherlands, now Netherlands Pat. No. 137,121 dated Mar. 16, 1973. The present invention incorporates means responsive to the position of the dome to shut the bilge disposal system down until the oil accumulated in the separator has been discharged in a particular manner as will be described in detail below, the oil discharge phase of operation also backwashing with clean water the oil coalescing screens used in the separator to further clean the bilge water being procesed before its discharge to the engine exhaust evaporator or overboard the vessel. An automatically regulated inverted dome-type oil-water separator with a pneumatic control system is commercially available from Hydrovac Systems International, Inc., Rockefeller Plaza, New York City, 10020, and is used in many applications for separating heavier and lighter fluid constituents. Separators of this type are especially advantageous aboard ship since they are relatively insensitive to ship motion or entrained gases or solids, fully enclosed, operable over a range of 0-100% oil to water ratio, operable with oils up to about 0.975 specific gravity, operable at virtually any temperature above freezing, and processed water can be discharged routinely with 10 parts per million (PPM) or less oil. In addition, an inverted dome oil separator of this type is especially adaptable for use in the fully automated bilge water disposal system of the present invention since it can be readily modified in accordance with the present invention to cooperate with an engine exhaust stack evaporator system to enable automatic, continuous bilge water disposal under a wide range of conditions.